In business it is of course important to have contingencies. A business will typically have a backup printer or have temporary staff they can call upon in a crisis. Why do they have these contingencies in place? A good manager would have identified the risk and spent time, prior to the risk actually turning into a problem, preparing a contingency plan for when the expected problems arise.
It is the same for data contingencies. A mirrored RAID system is great for backing up and preventing loss of data. However what happens if data placed onto a RAID system is overwritten by mistake with invalid data or the data is deleted? Ultimately these problems described occur through human error. They are though, real risks that have to be identified and managed.
A RAID system will not help in these scenarios, because a RAID system has no sense of time. They will only help a business to retrieve the data that was on them at the point in time that one of their hard disks fail. Whether that data is correct or not is another matter because, for example, 3 weeks earlier a member of staff might have deleted some crucial data by mistake.
The solution is to deploy a point-in-time backup system that backs up the data that is held in the RAID array to a third party device or hard disk at specified intervals. When a business discovers that its current data is not valid it can “roll back the clock” and look at that data at an earlier point in time. How far back the backup system can go depends on the backup system’s available memory.
For larger businesses that have hundreds of Gigabytes of data and who want to be able to roll back up to 7 years, this might sound expensive. There are some products available that can perform differential backups, which means it only backs up the sections of the data that have changed since the last backup. Which saves a lot of backup hard disk space.